Electric valve protective system



E. FAssLER 2,063,237

ELECTRIC VALVE PROTECTIVE SYSTEM Filed March 7, 1954 Patented Dec. 8, 1936 UNITED STATES PATENT OFFICE ELECTRIC VALVE PROTECTIVE SYSTEM Switzerland Application March 7, 1934, Serial No. 714,396 In Germany March 7, 1933 n Claims.

This invention relates in general to improvements in protective systems and more particularly to systems for protecting an electric valve, used to supply an inductive output circuit, against disturbances occurring in the circuit thereof.

It is well known that the flow of current through an electric valve energized from a source of alternating current may be interrupted upon occurrence of a disturbance by negatively energizing the control electrodes of the valve with respect to the associated cathode. If the valve is of the vapor type, the flow of current through the anodes thereof is not instantly interrupted by the action of the control electrodes, but the control electrodes prevent the transfer of the flow of current between the several anodes during the voltage cycle of the source so that the flow of current through the valve ultimately ceases. To avoid valve damage resulting from a protracted flow of excessive currents therethrough, such currents should be interrupted in the shortest possible time following their initiation. Such interruption should also occur rapidly to avoid destruction of a current consuming device, such as a radio transmitting tube supplied by the valve, upon occurrence of a flashover there-in. If the output circuit of the valve is of inductive character, however, the flow of current tends to continue irrespective of the action of the control electrodes until the magnetic energy stored in the inductive portions of the circuit is dissipated to a substantial extent. Such action may be avoided by so controlling the valve upon occurrence of a disturbance that such valve operates to return, to the source, the magnetic energy stored in the inductive portion of the circuit thereby causing such energy to be removed very rapidly. When. several valves are serially connected, all the valves are preferably controlled in the above manner to avoid occurrence of circulating currents therebetween. If so desired, the discharge of the inductive means may be aided by connection therewith of suitable impedance means providing another path for the flow of discharge current.

It is therefore one of the objects of the present invention to provide a protective system for an electric valve supplying an inductive output circuit, by which the flow of energy through the valve may be reversed upon occurrence of a disturbance.

Another object of the present invention is to provide a protective system for an electric valve supplying an inductive output circuit, by which the interruption of the flow of current through the valve is not affected by the inductance of the output circuit connected therewith.

Another object of the present invention is to provide a protective system for an electric valve supplying an inductive output circuit, by which the inductive energy stored in the output circuit of the valve is returned to the supply circuit upon occurrence of a disturbance.

Another object of the present invention is to provide a protective system for an electric valve supplying an induction output circuit, by which the flow of current through the valve is interrupted upon occurrence of a short circuit in the output circuit thereof and is not reestablished until such short circuit is removed.

Another object of the present invention is to provide a protective system for an electric valve I supplying an inductive output circuit, by which the flow of energy is simultaneously reversed through a plurality of serially connected valves upon occurrence of a disturbance.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing which diagrammatically illustrates embodiments of the present invention applied to the control of two serially connected electric valves normally converting alternating current into direct current.

Referring more particularly to the drawing by characters of reference, the reference numeral 6 designates an alternating current supp-1y line herein represented as a three phase line. Line 6 is connected through a circuit breaker I with the primary windings of two supply transformers 8 and 9. Transformer 8 is provided with a secondary winding having a plurality of phase displaced portions interconnected in any manner known in the art and severally connected with the anodes II of an electric valve I2 having a cathode I3. The secondary winding of transformer 9 is similarly connected with the anodes I4 of a second electric valve I6 having a cathode II. Valves I2 and I6 are provided with the usual discharge igniting and maintaining means, which are well known and are therefore not shown. The secondary winding of transformer 9 is connected with cathode I3 and the secondary winding of transformer 8 is connected with the negative conductor I8 of a direct current line having a positive conductor I9 connected with cathode I'I. Line I8, I9 is assumed to be of inductive character as a result, for example, of the presence of a reactor 2| inserted in conductor I9.

The flow of current through anodes H is controlled by means of control electrodes 22 severally associated therewith and the flow of current through anodes I4 is similarly controlled by means of similarly associated control electrodes Cathode l3 will be taken as datum for the 'otentials of the several control electrodes 22 cathode ii will be taken as datum for the otentials impressed on the control electrodes 23. .ry electromotive forces or potential difierences lpressed between a control electrode and the scciated cathode will then have the same value as the potential of the control electrode. Durin norr.a1 operation of the system control electro'es 22 are not connected with any source of potential, the construction of such control electrodes being assumed to be such that, under such conditions, flow of currents can occur through anodes H to cause transfer of energy from line 5 to line l8, i

To produce energization of control electrodes 22 upon occurrence of a disturbance, a source of control potentials such as a battery 24 is provided, the negative terminal thereof being connected with control electrodes 22 through resistors and 2". and through contacts 28 of a relay A voltage divider 33 having an intermediate tap connected with cathode |3 is connected across the terminals of battery 24 to thereby maintain the potentials of such terminals in definite relation with the potential of cathode l3. The positive terminal of battery 24 is connected through contacts 29 of relay 32 with the brush of a distributor 36. Each segment of distributor 36 is connected with one of the control electrodes 22 through the associated resistor 26. The brush is driven in relation with the voltage cycle of line 6 by suitable means such as a synchronous motor 31 energized from line 6 through a switch 55. The field of motor 31 is provided with a plurality of windings energized with direct current from a suitable source such as battery 24 through a rheostat 38, adjustment of such rheostat causing a corresponding change in the times of engagement of brush 34 with the several contacts of distributor 36 during the voltage cycle of line 6.

During normal operation of valve l6, control electrodes are energized to cause such control electrodes to control the flow of current through the associated anodes l4. Each control electrode 23 is accordingly connected through resistors 39 and 4| with the negative terminal of second battery 42 connected with cathode [1 through a voltage divider 43. The positive terminal of battery a2 is connected with the control electrodes through resistors 39 and segments of a distributor 5i, brush 49 of such distributor and contacts 4 of a second relay 48. Brush 49 is en in relation with the voltage cycle of line om a second synchronous motor 53. The times of energization of control electrodes 23 dur'ng the voltage cycle of line 6 may be adjusted by a rheostat 54 controlling the connection of the several field windings of motor 53 with battery The positive terminal of battery 42 is connectd with the control electrodes 23 through resisors 33, contacts 46 of relay 48 and a second brush c2 of distributor 5| to energize such control electrodes in a manner similar to the manner of energization of control electrodes 22. Relays 32 and G8 are each provided with an operating coil, such coils being preferably serially connected with a resistor 58 and being energized from ourrent transformers 56 and 51 inserted in the connections between lines 6 and the primary windings of transformers 8 and 9. Such coils may also be energized from the secondary Winding of a current transformer 59 connected in series with a resistor 6| and a spark gap or similar arcing device 62 to form a bridging connection across reactor 2|. The coils may also be energized from a battery 64 having the negative terminal thereof connected with conductor IB, the connection thereof with the coils being completed through a resistor 61, a reactor 68, contacts 3| and 41 of the relays, conductor l9 and the load connected therewith. Resistor 58 reduces the useless flow of current from battery 64 through the current transformers and reactor 68 substantially prevents the flow of current from the current transformers to battery 64. It will be understood that although relays 32 and 48 are shown as being each provided with only one coil, each relay may be provided with a plurality of coils severally energized from current transformers 56, 51 and 59 and battery 64 if so desired. Relays 32 and 48 are so constructed as to operate instantly upon energization of the coils-thereof and may be provided with means for delaying the return of the relays to the position shown in the drawingv Current transformers 56, 51 and 59 may be short circuited by a time delay relay 63 having the coil thereof energized from battery 64 through auxiliary contacts 86 of circuit breaker to prevent undesired operation of relays 32 and 48 in response to the current surge resulting from the closure of circuit breaker In operation, the system being connected as shown and line 6 being energized, upon closure of switch 55 synchronous motors 31 and 53 are started and brought to the synchronous speed thereof by any well known means (not shown). Control electrodes 22 then remain unenergized, and control electrodes 23 are energized at a negative potential from battery 42 through resistors 39 and 4|. Such control electrodes are thereafter energized at a positive potential from battery 42 through contacts 44, brush 49 and the several segments of distributor 5| in sequence in relation with the voltage cycle of line 6 to release the flow of current sequentially through the several anodes M, the output voltage of valve |G being regulated by adjustment of rheostat 54. Upon closure of circuit breaker 1, transformers 8 and 9 are energized and supply alternating currents to valves l2 and I6 whereby such currents are rectified and supplied to line I8, l9 and to the current consuming devices (not shown) connected therewith. Such flow of current occurs at the unregulated output voltage of valve |2 plus the output voltage of valve I6 regulated by suitable adjustment of rheostat 54.

Upon occurrence of a short circuit in line I8, |9 the direct current output voltage of the valves is suddenly impressed across the terminals of reactor 2|. Gap 62 is so adjusted as to then break down, thereby providing a path for the discharge of the magnetic energy stored within reactor 2|, such energy being dissipated in the resistor 6|. The resulting initiation of the flow of current through current transformer 59 causes the appearance, at the secondary terminals thereof, of a voltage impulse impressed on the coils of relays 32 and 48 through resistor 58 to cause operation of the relays. The fiow of short circuit current through valves l2 and I6 and conductors l8 and |9 also causes the flow of excessive currents through current transformers 56 and 51. Current transformers 56 and 51 there fore impress, on the coils of relays 32 and 48, voltages of sufficient magnitude to cause operation of such relays, such voltages being impressed on the coils somewhat later than the impulse from current transformer 59 and causing operation of the relays even if gap 62 fails to break down. Upon operation of relays 22 and 48, control electrodes 32 and 23 receive, from batteries 24 and 42 through distributors 36 and respectively, potentials of signs and magnitudes and at recurring intervals effective to cause valves l2 and Hi to invert direct current from line 8, Hi into alternating current supplied thereby to line 6. The magnetic energy stored in reactor 2|, which is partially dissipated by flow of current from reactor 2| through resistor 6|, is thus substantially coincidentally also dissipated by flow of current through conductor l9, the short circuit fault, conductor I8 and valves l2 and IS, the energy conveyed by such current being transferred to line 6 through valves i2 and i6 and transformers 8 and 9. Brushes 3,4 and 52 are so adjusted that the flow of energy thus initiated continues until the discharge of reactor 2| is substantially complete. The adjustment of brush 52 is somewhat affected by adjustment of rheostat 54, but if so desired separate means may be utilized for the adjustments of brushes 4a and 52.

Upon complete discharge of reactor 2|, the flow of current through valves |2 and |B ceases completely as the valves are then operable only to transfer energy from line l8, $9 to line 6 from devices connected with line 58, I9 and capable of impressing a reverse voltage on such line whereby conductor i8 is made positive and conductor l9 negative, as occurs during the discharge of reactor 2|. Relays 32 and 48 having operated, the coils thereof remain energized from battery 54 through resistor 61, reactor 68, contacts 3| and il, conductor l9, the short circuit fault and conductor l8. The relays therefore maintain the connections between batteries and 42 and distributors 5| and 36 as long as the short circuit fault is present. Upon removal of the short circuit, the flow of current through the coils of relays 32 and 48 must take place through the load consuming devices and is accordingly reduced to an extent sufli'cient to cause relays 32 and 48 to return to the position shown in the drawing. Valves l2 and Hi are then returned to the normal operative condition thereof and the flow of current therethrough is reestablished.

Upon occurrence of a backfire in valve l2 or in valve IS the flow of current therethrough is interrupted and the energy of reactor 2| is dissipated in a manner similar to that outlined above.

It will be understood that instead of utilizing two valves in series connection as shown in the drawing it is also possible to utilize only one valve controlled either as valve l2 or as valve l6 are controlled. Resistor 6i and gap 62 may also be omitted, current transformer 59 then becoming unnecessary.

Valves l2 and I6 and transformers 8 and 9 therefore constitute electric translation means for normally transmitting electrical energy from line 6 to line l8, l9. Reactor 2| constitutes inductive means and therefore also energy storage means in line l5, l9. Control electrodes 22 and 23 and the associated apparatus operate in response to abnormal conditions or to the occurrence of a disturbance in the translation means for momentarily causing reversal of the flow of energy therethrough and transmission of energy from line l8, l9 to line 6 by way of valves I2 and i5, thus causing discharge of the magnetic energy of reactor 2| into line 6. Distributor 5| energizes control electrodes 23 from battery 42 to cause transfer of energy from line 6 to line Iii, l9 by way of valve H5, and relay 48 operates in response to the occurrence of a disturbance in the system to modify the action of distributor 5! for momentarily causing reversal of the flow of energy through valve Distributor 36 is operable to energize control electrodes 22 from battery 24 to cause transfer of energy from line I8, 59 to line (i by way of valve I2, relay 32 operating in response to the occurrence of abnormal conditions within the system for causing mementary operation of distributor 3%. Relay 48 operates in response to the flow of excessive current through valve I6 and also in response to the magnitude of the voltage across reactor 2|. Relay 48 and the associated apparatus energize control electrodes 23 from battery 42 to cause transfer of energy from line |8, |9 to line 6 upon occurrence of a short circuit, battery (it and connections thereof maintaining the operation of relay d8 until removal of the fault. During presence of the short circuit fault therefore relay 48 and battery 64 and distributor 5i maintain control electrodes 23 at potentials of signs and magnitudes effective to prevent transmission of energy from line 6 to line l8, l9 by way of valve l6. Resistor 5| constitutes impedance means connected with reactor 2|, and gap 22 constitutes means for discharging reactor 2| through resistor 6| substantially coincidentally with the discharge of reactor 2| into line t by way of valve it.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In an electric valve protective system, an

alternating current supply circuit, an electric valve connected with said circuit, a. direct current output circuit connected with said valve, energy storage means in said output circuit, and means responsive to the presence of a short circuit condition in said direct current circuit for causing discharge of the energy of the first said means into said alternating current circuit by way of said valve.

2. In an electric valve protective system, an alternating current supply line, electric valve means connected with said line and having an anode with an associated control electrode and a cathode, a direct current output line connected with said valve means, inductive means in said direct current line, and means responsive to the presence of short circuit conditions in said direct current line for discharging the magnetic energy of said inductive means into said alternating current line by way of said valve means.

3. In an electric valve protective system, an alternating current supply line, electric valve means connected with said line and having an anode with an associated control electrode and a cathode, a direct current output line connected with said valve means, inductive means in said direct current line, a source of control potentials, means for energizing said control electrode from said source to cause transfer of energy in one direction between said lines by way of said valve means, and means responsive to the occurrence of a disturbance in the system for modifying the action of the third said means for momentarily causing the flow of energy stored within said inductive means through said valve means.

4. In an electric valve protective system, an alternating current supply line, an electric valve connected with said line and having an anode with an associated control electrode and a cathode, a direct current output line connected with said valve, inductive means in said direct current line, a source of control potentials, means for energizing said control electrode from said source operable to cause transfer of energy stored within said inductive means into said alternating current line by way of said valve, and means responsive to the occurrence of abnormal conditions within the system for causing momentary operation of the second said means.

5. In an electric valve protective system, an alternating current supply line, electric valve means connected with said line and having an anode with an associated control electrode and a cathode, a direct current output line connected with said valve means, inductive means in said direct current line, a source of control potentials, means for energizing said control electrode from said source to cause transfer of energy from said alternating current line to said direct current line by way of said valve means, and means responsive to the occurrence of a disturbance in the system for temporarily energizing said control electrode from said source to cause transfer of energy from said direct current line to said alternating current line by way of said valve means.

6. In an electric valve protective system, an alternating current supply line, electric valve means connected with said line and having an anode with an associated control electrode and a cathode, a direct current output line connected with said valve means, inductive means in said direct current line, and means responsive to the flow of excessive current through said valve means for discharging the magnetic energy of said inductive means into said alternating current line by way of said valve means.

7. In an electric valve protective system, an alternating current supply line, electric valve means connected with said line and having an anode with an associated control electrode and a cathode, a direct current output line connected with said valve means, inductive means in said direct current line, and means operable upon the occurrence of short circuit conditions in said direct current line for discharging the magnetic energy of said inductive means into said alternating current line by way of said valve means, the third said means being responsive to the magnitude of the voltage across the said inductive means.

8. In an electric valve protective system, an alternating current supply line, electric valve means connected with said line and having an anode with an associated control electrode and a cathode, a direct current output line connected with said valve means, inductive means in said direct current line, means responsive to the occurrence of a short circuit in said direct current line for temporarily energizing said control electrode from said source to cause transfer of energy from said direct current line to said alternating current line by way of said valve means, and means maintaining the operation of the last said means until removal of the short circuit.

9. In an electric valve protective system, an alternating current supply line, electric valve means connected with said line and having an anode with an associated control electrode and a cathode, a direct current output line connected with said valve means, inductive means in said direct current line, impedance means connected with said inductive means, and means responsive to the occurrence of a disturbance in the system for discharging the magnetic energy of said inductive means through said impedance means and substantially coincidentally therewith into said alternating current line by way of said valve means.

10. In a system of the character described, the combination with an electric current supply circuit, an electric current load circuit having energy storage means included therein, and a plurality of serially connected electric valves interconnecting said circuits for the transfer of energy therebetween, of means operable, responsive to the occurrence of a disturbance in said load circuit, for causing the discharge of energy stored in the first said means into the said supply circuit by way of said valves.

EMMANUEL FiissLER. 

